Apparatus for laboratory testing



Sept- 6, 1965 D. L. WILLIAMS ETAI..v 3,271,112

APPARATUS FOR LABORATORY TESTING 2 She ets-Sheet l Filed Deo. 12, 1962 S ,mum 2mm ma l T A iw www M D QH/Z2 f ATTORNEYQ FIG. .3

United States Patent O 3 271 112 APPARATUS FOR LAORATORY TESTING Donald L. Williams, 1687 N. 17th, Coos Bay, Oreg., and Robert D. Pence, 363 N. Commercial, Empire, Greg. Filed Dec. 12, 1962, Ser. No. 244,160 Claims. (Cl. 23-253) This invention relates in general to a method and apparatus for making laboratory tests and more particularly to a method and apparatus for use in blood plasma prothrombin determination.

In making blood plasma prothrombin determination, blood plasma is usually placed in a test tube and heated to a temperature between 37 C. and 38 C. and then various clotting reagents are placed in the blood plasma which create a clot formation. The time between the insertion of the clotting reagent and the clot formation determines the particular condition of the patents blood. The timing must 'be accurate within two seconds. Maintenance of the blood plasma and clotting reagent at a constant temperature throughout the performance of this test is an important factor in the accuracy of the test.

Prior art devices employ a control heat water bath in which diiiculty is encountered in accurately controlling the temperature and observing the mixture being tested.

The object of this invention is to provide a method and apparatus whereby the blood plasma and clotting solution can be maintained at a constant temperature throughout the test.

Another object of the invention is to provide a method and apparatus in which a magnified image :of the mixed blood plasma and clotting solution may be observed for a more accurate determination of the clotting time.

Another object of this invention is to provide a laboratory apparatus which is simple in construction and easily accessible for multiple tests yet accurate in operation.

According to this invention the preheating and viewing chambers are made in a single block, the temperature of which is maintained constant to assure uniform heat throughout the test and the viewing chamber is provided with a magnifying mirror to allow a closer inspection of the mixture tested.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing in which:

FIG. l shows a perspective view of the testing device according to this invention;

FIG. 2 is a side elevation of the testing device as appears when viewed from the rear side;

FIG. 3 is a cross-sectional view taken along line 3 3 of FIG. 3;

FIG. 4 is a fragmentary cross-sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is a top plan View of the testing device;

FIG. 6 is a right hand end elevation view of the testing device of FIG. 5; and

FIG. 7 is an electric circuit diagram for control of the testing device.

Referring to FIG. 1 there is shown a block 10 preferably made of aluminum reduce lweight but other metals having good heat conductive properties are also suitable. Block 10 has a plurality of te-st tube holders 11 and 12 made by providing holes therein to support a plurality of test tubes 13 and 14, respectively. Test tubes 13 and 14 contain the materials to be tested which are preheated when placed in the respective test tube holders 11 and 12.

Viewing chamber 15 is made yby providing `an inclined hole in block 10. A test tube holder 16 for sup- 34,27 1,1 l2 Patented Sept. 6, 1966 porting the test tube within the viewing chamber is made by providing an inclined hole in block 10. Light holder 17 containing a light 18 is made by providing an inclined hole in block 10. Light 18 illuminates the mixture to be tested which is placed in viewing chamber 15. Both test tu'be holder 16 and light holder 17 communicate with viewing chamber 15 as is illustrated in FIG. 3.

A base plate 19 is attached to block 10 by a plurality of bolts 20. Rubber mountings 21 are held by bolts 20 and serve as a cushion between the testing device and laboratory ta'ble. Base plate 19 is made of the same material as block 10 to insure uniform heating. Base plate 19 is detachable from block 10 to allow mounting of terminal blocks 33 and 34 in base plate 19 and strip heaters 27 and 28 in block 10. Strip heaters 27 and 28 extend along the lower portion of block 10 as noted in FIGS. 2 and 4.

Block 10 has a control box portion 35 for supporting some of the electrical components. Control box portion 35 can be an integral part block 10 as shown or an individual box fabricated from a material similar to that of block 10. Control box portion 35 supports pilot light 22, heater switch 23, and light switch 24 as is shown in FIG. 1. Transformer 30 is mounted inside control box portion 35 as is shown in FIG. 2. A door 36 is secured by screws 37 or other suitable fasteners to enclose control box portion 35.

Referring to FIG. 3, the viewing chamber 15 has a lens 26 of transparent material such as glass or plastic mounted across the top portion to contain the heat therein and accommodate visual inspection of the interior of viewing chamber. The lower portion of viewing chamber 15 is closed by a plug 32 made of steel which supports a layer of bedding compound 31. Resting on bedding compound 31 is a mirror 25 of selected magnification. In a working model `of the invention a mirror of approximately two magnifications was found suitablel In testing, the reaction is viewed in the mirror to allow a more careful inspection yof the mixture. Light 18 is counted in light holder 17 and illuminates the mixture to be tested. Electrical cord 38 extends from light 18 through a vertical opening 39 in block 10 and then along a groove 40 in base plate 19 to control box portion 35.

Thermostat 29 is placed in block 10 extending from control box portion 35 and is located `between test tube holders 11 and 12 as shown in tFlG. 5. This control location allows thermostat 29 to make an accurate determination of the temperature of the complete testing device and allows its removal through the control box door 36.

FIG. 7 `shows the electrical connections of the various electrical components mentioned above. Strip heaters 27 and 28 are electrically connected in parallel. This parallel combination is connected in series with thermostat y29 and heater switch 23 and then to power supply 41. Power supply 41 is usually the conventional 110 volt 6() cycle alternating current supplied to medical laboratories but all of the electrical components can be modified to operate on the power supply available. A pilot light 22 is connected in parallel with strip heaters 27 and 28 to indicate when power i-s being supplied to the heaters. Upon closing of switch 23 the voltage of power supply 41 is applied to strip heaters 27 and -28 until thermostat 29 or switch 23 opens the circuit.

Electrical power to light 18 which illuminates the mixture to be tested in the viewing chamber 15 is supplied by power supply 41 through transformer 130. Transformer 30 has a primary winding 42 and a secondary winding 43 which steps down the voltage. Light 18 is serially connected to secondary winding 43. Light switch 24 is serially connected to primary winding 42 and the combination connected to power supply 41 so that upon closure of switch 24 the entire voltage across power supply 41 is across primary winding 42. When the power supply V41 is 110 volts the voltage which appears across secondary winding 43 is 6 volts which is used to power a 6 volt bulb of light 118. It is apparent that upon closure of switch 24 light 18 will be actuated, thus lighting vie-wing chamber 115.

The operation of the testing device to test for blood plasma prothrombin determination is as follows: Switches 2'3 and 24 are closed to heat block 10 and illuminate viewing chamber 15, respectively. Selected amounts of blood plasma and a clotting solution are placed in test tubes 13 or v114 and then placed in holder `11 or 12 for preheating. Thermostat 29 maintains block 10 at the preselected temperature of 37 C., which is approximately body ternperature, by opening and closing the electric circuit to power supply 41. After the blood plasma and clotting solution have been suticiently preheated a test tube containing blood plasma is placed in holder 16 where it can be observed through lens 26 and in the mirror 25. Then the clotting solution is added to the blood plasma and the length of time it takes to `clot is recorded. 'By =hav ing the viewing chamber 15 and test tube holder 11 a part of a single block 10, uniform heating throughout the test is assured. Further, by being able to observe a magnified image of the mixture of blood plasma and clotting solution a more accurate time determination can be made. It is apparent that the structure is easily ac cessible and that once block 10 has heated to 37 C. many tests can be run in a short period of time.

Although we have described our invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and the numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

We claim as our invention:

1. Apparatus for determining prothrombin time in blood plasma comprising a housing, means for heating said housing and maintaining it at a predetermined ternperature, said housing being of material having a good heat conductivity characteristic whereby said housing has a uniform temperature, rst container means for carrying yblood plasma to be tested, storage means in said lhousing for said rst container means whereby said blood plasma is preheated to said predetermined temperature prior to the measurement of prothrombin time, viewing chamber means substantially fully enclosed by said housing and adapted to receive at least a portion of said first container means, means for illuminating said viewing chamber, and lmeans for viewing that portion of said rst container which is inserted into said chamber, said viewing chamber being substantially closed to the ambient atmosphere and being maintained at said predetermined temperature whereby said prothrombin time may be accurately determined.

2. The apparatus of claim 1, wherein said means for heating said housing and maintaining it at a predetermined temperature comprises electrical strip heaters mounted within said housing and thermostat means for controlling the dlow of electricity thereto in accordance with the temperature of said housing.

3. The apparatus of claim 1, wherein said first container means comprises a test tube, said storage means comprising at least one test tube holder extending into said housing.

4. The apparatus of claim 1, wherein said viewing chamber means comprises an opening within said housing, at least a portion of said opening extending to one surface of said housing, said viewing chamber means further including means for supporting said iirst container means, transparent means for closing the portion of said opening which extends to said one surface of said housing, and mirror means within said viewing chamber means to accommodate visual inspection of said blood plasma during said determination of prothrombin time, said mirror being concave to provide magnification.

5. The apparatus of claim 1, further including second container means for carrying solution to be added to said blood plasma when said prothrombin time is to be measured, said rst and second container means comprising test tubes, and said storage means comprising a plurality of test tube holders extending into said housing.

References Cited by the Examiner UNITED STATES PATENTS r2,041,290 5/ 1936 Jackson 88-14 2,276,021 4/1941 Copley et a1. 128-2 2,878,715 3/1959 Rhees 88-l4 3,041,146 6/.1962 -Kuzell 23-253 3,158,445 l'l/1964 Huff 23-253 MORRIS O. WOLK, Primary Examiner. JOSEPH SCOVRONEK, Z. JAROCZAY, Examiners. 

1. APPARATUS FOR DETERMINING PROTHROMBIN TIME IN BLOOD PLASMA COMPRISING A HOUSING, MEANS FOR HEATING SAID HOUSING AND MAINTAINING IT AT A PREDETERMINED TEMPERATURE, SAID HOUSING BEING OF MATERIAL HAVING A GOOD HEAT CONDUCTIVITY CHARACTERISTIC WHEREBY SAID HOUSING HAS A UNIFORM TEMPERATURE, FIRST CONTAINER MEANS FOR CARRYING BLOOD PLASMA TO BE TESTED, STORAGE MEANS IN SAID HOUSING FOR SAID FIRST CONTAINER MEANS WHEREBY SAID BLOOD PLASMA IS PREHEATED TO SAID PREDETERMINED TEMPERATURE PRIOR TO THE MEASUREMENT OF POTHROMBIN TIME, VIEWING CHAMBER MEANS SUBSTANTIALLY FULLY ENCLOSED BY SAID HOUSING AND ADAPTED TO RECEIVE AT LEAST A PORTION OF SAID FIRST CONTAINER MEANS, MEANS FOR ILLUMINATING SAID VIEWING 